1. Field of the Invention
The present invention relates to a method of producing a buried-type multilayer interconnection structure, and more particularly, to a method of producing a buried-type multilayer interconnection structure by a physical vacuum deposition method.
2. Description of the Related Art
A method of producing a buried copper interconnection by a conventional Damascene process requires that after a barrier metal layer of TaN or the like is formed within a via hole, a seed layer is formed on the barrier metal layer, and the via hole is buried up by electroless plating which uses the seed layer (JP, 2000-336486, A, S. Shingubara, T. Ida, H. Sawa, H. Sakaue, and T. Takahaghi: “Effect of Pd Catalyst Adsorption on Cu Filling Characteristics in Electroless Plating,” Advanced Metallization Conference 2000, Mat. Res. Sci. Conf. Proc. ULSI-XVI (2001), pp. 229–234).
FIGS. 5A–5D show cross sectional views of steps of producing a conventional buried copper interconnection. These steps include the following steps 1–4.
Step 1: As shown in FIG. 5A, a hole portion 52 is formed in an interlayer insulating film 51 of silicon oxide for instance, following which a barrier metal layer 53 of TaN or the like is formed on a surface of the hole portion 52 by a sputtering method.
Step 2: As shown in FIG. 5B, after tin is adsorbed on a surface of the barrier metal layer 53 or the like by a wet method using a tin chloride solution, tin is substituted with palladium using a palladium chloride solution and palladium (Pd) colloid particles 54 are adsorbed (wet method).
Step 3: As shown in FIG. 5C, by electroless plating which uses the palladium colloid particles 54 as a catalyst, a seed layer 55 of Cu whose film thickness is about 10 nm is formed.
Step 4: As shown in FIG. 5D, as the seed layer 55 of Cu is formed through electroless plating, the seed layer 55 is formed also within the hole portion 52 which has a large aspect ratio. Following this, by electrolytic plating which uses the seed layer 55, the hole portion 52 is buried up with Cu and a buried interconnection is therefore obtained (not shown).